1. Field of the Invention
This invention relates to switch assemblies of the kind which are intended to be both robust and weather resistant.
2. Discussion of Prior Art
There is a need for robust and weather resistant switch assemblies in many applications, but a notable application is the "key-pad" of exterior Automatic Teller Machines at banks and similar financial institutions.
Numerous "keyboard" type switch assemblies are known but few address the joint requirements of being "environmentproof" and sufficiently robust to resist, for example, vandalism. U.S. Pat. No. 3,617,660 discloses a switch assembly where attention has been given to moisture protection and to the problems of actuator overtravel. However the solution to the actuator overtravel problem proposed in U.S. Pat. No. 3,617,660 is to transmit actuation movement to the electrical contacts by way of resiliently deformable components which deform to accommodate overtravel of the actuator beyond the position at which the contacts close. Such an arrangement produces a switch "feel" which is spongy and imprecise and moreover while it can accommodate simple overtravel of the actuator it appears unable to accommodate the kind of overloading which can occur in a vandal attack. It is an object of the present invention to provide a switch assembly with improved resistance to attack, both environmental and human.